1. Field of the Invention
The present invention is directed to a manually operated dispensing pump and more particularly to a container-mounted, finger-operated pump incorporating a deformable pump wall, elastomeric inlet and outlet valves and a positive shut-off.
2. Brief Description of Background Art
Container-mounted, finger-operated dispensing pumps are well known and are used for dispensing liquids having widely varying flow characteristics. The form of discharge from these pumps can vary from a fine spray to a slow moving flow.
Typically, container-mounted dispensing pumps employ fixed and movable pump members forming a variable volume pump chamber and one-way valves controlling the flow into and out of the pump chamber. Various types of one-way valves, including ball check valves and elastomeric valves, are employed in these dispensing pumps.
Many container-mounted dispensing pumps incorporate a feature which allows them to be placed in a xe2x80x9cshippingxe2x80x9d position to prevent leakage through the pump if they are upended or if the container contents become pressurized. A common pump of this type employs a reciprocable plunger which can be locked in a depressed position, holding a ball check valve closed to seal the pump against leakage. Applicants are not aware of dispensing pumps which incorporate a deformable pump wall and elastomeric pump valves and which can be placed in a shipping position to prevent leakage through the pump.
An object of the present invention is to provide a dispensing pump which operates reliably and which is inexpensive to manufacture.
Another object of the present invention is to provide a dispensing pump employing a deformable pump wall and elastomeric pump valves.
Yet another object of the present invention is to provide a container-mounted dispensing pump incorporating a deformable pump wall and a positive shut-off mechanism for an elastomeric pump valve which precludes leakage of the container contents through the pump.
The foregoing objects of the invention, and others as well, are realized in the dispensing pump of the present invention which incorporates a stationary pump member and a deformable pump wall having one end thereof engaging the stationary pump member with a sliding seal to thereby form a variable volume pump chamber, an elastomeric valve controlling the flow of liquid from the pump chamber and a positive shut-off mechanism for applying a positive closing force to the elastomeric valve to prevent leakage through the pump. In a preferred embodiment of the dispensing pump, at least part of the deformable pump wall is a self-restoring bellows.
The objects of the invention are also realized by a dispensing pump comprising: a pump base provided with means for attachment to a container of a liquid to be dispensed; an inlet passage extending through the pump base; an elastically deformable pump wall having (1) a stationary end sealed to the pump base about the inlet passage and (2) a movable end, the deformable pump wall surrounding and defining a variable volume pump chamber; an actuator with a dispensing head coupled to the movable end of the pump wall for movement therewith between (1) an extended position at which the volume of the pump chamber is enlarged and (2) a depressed position at which the volume of the pump chamber is reduced; a one-way inlet valve controlling the flow of liquid into the pump chamber through the inlet passage; means forming an outlet passage accommodating flow of liquid from the pump chamber to the dispensing head; an elastomeric one-way outlet valve controlling the flow of liquid from the pump chamber to the dispensing head through the outlet passage; and means for engaging and applying a closing force to the outlet valve in response to movement of the actuator to the extended position thereof.
In one embodiment of the dispensing pump, the elastomeric valve is an O-ring engaging a seat on the stationary pump member, and the shut off mechanism comprises a formation on the movable end of the pump wall that engages the O-ring when the volume of the pump chamber is enlarged to press the O-ring against its seat.
In another embodiment of the dispensing pump, the elastomeric valve is a duckbill valve carried on the stationary pump member, and the shut off mechanism comprises a formation on the movable end of the pump wall that engages movable pinching elements adjacent to the outlet end of the duckbill valve when the volume of the pump chamber is enlarged; the pinching elements, when engaged by the formation on the movable end of the pump wall, press the lips of the duckbill valve together to close the valve outlet passage.
In another embodiment of the dispensing pump, a segmented ring carried at the movable upper end of the deformable pump wall presses an O-ring into a valve seat controlling outlet passages through a formation at the upper end of the deformable pump wall.
All embodiments of the dispensing pump can also employ an elastomeric valve for controlling flow into the pump chamber, and this valve can be like the valve controlling the flow from the pump chamber, to minimize the number of different parts needed for assembly of the pump.
The positive shut-off mechanism can include a pump actuator coupled to the movable end of the deformable pump wall for movement therewith between extended and depressed positions corresponding, respectively, to enlarged and reduced volumes of the pump chamber. An element carried by the actuator can be moved to engage a formation on a stationary shroud about the pump for locking the actuator in the extended, shipping position.
The detailed description provided below together with the accompanying drawings will afford a further understanding of the present invention. Specific embodiments of the present invention which are disclosed herein should be regarded as illustrative and not restrictive of the scope of the invention.